The objective of this research is the development of comprehensive analytical and numerical models of pulsatile microcirculatory networks. The research is thus concerned with both the rheology of blood in small vessels and the interaction of the flow with the contiguous tissue. The long-term goal is to provide tools for the analysis of microcirculatory functions, for the analysis of organ-perfusion and artificial-organ requirements, and for the development of diagnostic and treatment methods for cardiovascular diseases. Previous work in this project has involved: (1) analysis of flow and mass transfer in capillary vessels, (2) development of a rheological model to account for non-Newtonian scale effects for blood flow in arteriole-sized vessels, (3) analysis of pulsatile non-Newtonian flow in arteriole-sized vessels, and (4) development of network models of pulsatile flow in compliant tissues. Our goals for the coming year are the refinement and extension of some of these component studies and their incorporation into comprehensive network models. A major component of our effort during the coming year will be devoted to the development of models which include the effects of the flow mechanics on mass transport between blood and tissue.